Vulcanizing process



Nov. 3, 1925. 1,559,702

E. HOPKINSON VULCANIZING PROCESS Origin a1 Filed Mal "ch '7, 1921 avwemtoz ERNEST HQPKINSON i975! as aw alt Mm, 3

Patented Nov. I 3, 1925.

UNITED STATES ERNEST HOPKINSON,

on NEW YORK, N. Y.'

VULGAINI ZING PROCESS.

Original application n edimamn 7, 1921, seriai iro. 450,193. Divided and this application filed January 8,1924. Serial No. 684,932.

To all whom it may concern:

I, Be it known that I, ERNEST HorKmsoN, a citizen of the United States, and ,a resident of New York city, county of New York, 'and State of New York, have invented a'certain new and useful Vulcanizing Process, of

which the following is a full, clear, and exact description. a

This invention relates to the manufacand more particularly, a process for simultaneously vulcanizmg them.

V This application is a division of my pend:

ing application, Serial No. 450,193, filed March 7th, 1921, issued as U. S. Patent 1,493,674 on May 13, 1924, and which in turn is a division of S. Patent 1,374,505, granted April 12, 1921.

Inner tubes are usually ,made and vul: canized on circular poles or mandrels in straight lengths. Afterwards, their ends are spliced to make a completeannulus, and the valve-stem mountedn The finished tubes are usually a little smaller on theirouter and a little larger on'their inner peripheries thanthe corresponding dimensionsof the cavity in the casing for which they are intended. I e

The present invention aims to provide a process for simultaneously vulcanizmg both the tubes and the casings so thatthe former may be utilized as an air-bag or fluid-eontainer for fluid under pressure which 1t 1S desirable to apply to the inside surfaces or ,5 walls of tire casings during their vulcanlzation. The finished tube substantially exactly fills the cavity of the casing in which it is vulcanized. The valve-stem is preferably utilized as a means for introducing fluid under pressure and is vulcanized in positlon so that possibility of leakage around the valve-stem is minimized. The stock for making the inner tube is spliced before its introduction in the casing inany manner suitable to hold fluid under pressure. The joints 10f the "tube, being subjected to fluid under pressure during vulcanization of both the tube and the casing, are necessarily cured in a fluid-tight condition. The vulcanized inner tube very nearly fits the cavity of the casing and, consequently, after both have been vulcanized and removed from the mold, the walls of the inner tube are not subjected to any substantial or objectionable amount ture of tubes and casings for motor vehicles,

of distension when inflated in service on a wheel rim. I Y d An embodiment of the invention is illustrated in the accompanying drawings, in which I Figure 1 is a cross-section of a mold-enclosing casing and tube; And Figure 2 is a cross-section of a completed tube.

In the drawings, the 'innertube is indicated at 1 and the casing at 2. The latter may be made of plies of fabric 3, cushion stocks 4 and 5, breaker strips 6 and 7, and tread stock 8,'in any desirable arrangement or relation, either as shown or varied in accordance with the practices obtaining among various manufacturers. But, preferably, the casing is, madeas disclosed in detail in Hopkinson Patent No. 1,374,505, grantedApril 7 12th, 1921.

The inner tube 1 3 preferably made of unv'ulcanized rubber composition- -withou t reinforcement excepting in the region of a valve-stem 9, where sections or patches 10' and 11 of rubberized fabric (woven or weftless are preferably incorporated. Any convenlent method may be employed to amass the rubber in hollow annular form. The l tube may be introduced into the casing" in either a green or semi-vulcanized condition. 1

Generally, the practice is to apply the reinforcing patches 10 and'll, then punch a-hole through the tube for the reception of the valve-stem 9, before the reen or semi-cured tube in introduced into t e casing.

The tube is mounted on" a' bull-ring 12, Whose function it is, in co-operation with an annular base 13 and mold members 14.

to give the exact size necessary to the bead portions 15 of the casing 2. The inner tube 1, after being mounted on the bull-rin 12,

is introduced into the casing 2, whic if made according to said Hopkinson Patent 1,374,505, does not fill the cavity in the mold sections 14.. The molding parts 13 and 14, and the clamps 16, are assembled, as shown in Figure 1, and fluid under pressure, preferably CO is. supplied to the tube 1, but any other suitable gas, or mixture. of gases,

suchras air'vor' liquid, may be employed if desired.

To prevent-the tube 1 from adhering to the casing 2 during vulcanization, itis slightly inflated and coated with glycerine,

talc, graphite, starch, powder mica, the paint powder known as aluminum bronze, or other suitable substance. Aluminum bronze is preferred as it imparts a beautiful silvery appearance to the finished casing and tube, and also serves as a lubricant in service; After coating the'tube 1, and also the casing 2,- if desired, as is preferable,

the two "are assembled ina mold, as already mentioned, and subjected to fluid under pressure, preferably around 180 pounds to the square inch.. The complete assemblage is then subjected to vulcanizing treatment,

in a French press or vulcanizer, for instance,

with steam at a pressure around laO pounds, yielding a heat in the neighborhood of 280 F. During vulcanization, the rubber softens somewhat and the casing is stretched so as to completely fill the cavity in andbe' pressed firmly against the mold sections 14 taking therefrom any design desired. to provide an anti-skid character-to the tread of the casing.

After vulcanization, the tube and easing are removed from the mold and the bullring. The tube may be left in the casing andsold therewith, as a complete unit, or it 'may tube is adapted to fill a casing in service without distension, at least in the region of the tread Where distension is undesirable. as it enhances, rather thandimnnshes, the l1a-' vbility of puncture.

It will be obvious that changes may be made'without departing from the principles underlying the invention and reference should therefore be made to the accompany- .ing claims for an understanding of its scope.

In the claims the term casin is used as 7 C! understood today, and refers to and comprehends only that construction of cover for an inner tube which is open throughout its entire inner circumference and is approximately U-shaped or'horseshoe-shaped incross-section. I y

Havin thus described my invention, What I c aim anddesire to protect by Letters Patent is:- p v 1. That method-of vulcanizing the tubes and casings which consists in, assembling an incompletely, vulcanized annular tube and casing in nested relation: with a, substance between'them preventing their union dur- 7 mg vulcanization,- completely enclosing the nestedtube and casing in mold members, and simultaneously vulcanlzlng both the tube and casing while malntaininga wallcompacting fluid pressure on the interior building a casing of strain-resistingelements and unvulcanizedrubber composition, making an inner tubeofincompletely vu'lcanized rubber. composition in an annular form and with a valve-stem mountedtherein, supporting the incompletely vulcanized inner tube upon an annular member of a Width adapted to close the space between the bead portions of the casing, nesting the thus-mounted tube within the casing, substantially, completely confining ,the nested tube and casing in molding members, and vulcanizing the assemblage whileapplying fluid under pressure to-the interior of the tube.

Signed at New York city, county of New York, and State of New York, this 3rdday of January, 1924.

ERNEST HOPKINSON.. 

